This proposed investigation will compare the neurophysiology of children (ages 8-12) and older adolescents and adults (ages > 14 years) who are characterized as having an early disorder of development. ERPs will be used to evaluate the brain-behavior relationships in people with autism, receptive developmental dysphasia, and their matched normal controls. We have already found evidence of differences in the physiology as measured by the ERP in adolescents and adults with autism and dysphasia. However, we do not know how this pathophysiology is expressed in younger autistic and dysphasic children and whether or not the differences we have found interact with the large developmental changes in electrophysiology and behavior that occur in normal children. The proposed experiments will examine both sensory and cognitive event related potentials in both auditory and visual paradigms. Our results will let us evaluate each of the several differences in components of the ERP which we already discovered between the clinical groups and normal controls. Specifically, we will examine P2, P3b, A/Pcz/300, and Nc in experiments designed to manipulate the sensory, attentional, and orientating mechanisms that may be abnormal in autism and dysphasia.